entry level price for a Nexus is about 26,000 US for a base model.you can't stack Nexus, you can extend the fabric, the nexus line is more of a data center swtich then an end user switch,so a 4500 or 6500 may be more appropriate,

is the plan 10G to the desktop ? that cost would be prohibitive,

and answers 1. no2. no3. yes

Tips of the day:- The human mind is the ultimate creation invention.- I have so many customers, my customers have customers. - Sausage time- POP, stack, and store

The Nexus like comprises of the 7K which is most like the 6500 in that its modular and has a bunch of power (virtually everything is upgradeable throughout the lifetime of the chassis).

The 5K is a fixed configuration switch which again has a bunch of power but isn't as configurable.

The 2K's are DUMB switches in that on their own they are a useless piece of metal, to work they need to be paired to a 5K or a 7K (with a specific line card) and they then appear just like a line card.

As ristau said the Nexus is more for a DC than for an end user deployment.

If you are looking at buying NEW 6500 chassis' for your servers then talk to your SE as you might find that the Nexus alternative is pretty similarly priced.

EDIT: By the way I am ignoring that there are some other devices in the Nexus range like the 1K which is used in VMware environments and the 3K which is a bit like the 4900 but I havent really studied them much so I can't comment on them.